1. Field of the Invention
The invention relates generally to systems and methods for determining position and clock offsets using radiated “signals of opportunity,” such as radio and television signals.
2. Background Information
Determining position is critical for high speed wireless networks that provide hand-offs to the nearest cell tower or other network devices. Further, position is critical for accurate time transfer over the network. GNSS receivers can provide position information, as long as the antennas at the remote locations have sufficiently clear views of the sky. However, there is a need for position information at remote locations that do not have such views of the sky and, in particular, at remote devices that may be located in buildings or other harsh environments for GNSS solutions.
One method for determining position using signals of opportunity is described in U.S. Pat. No. 6,492,945 to Counselman. The Counselman method, which determines instantaneous position of a moving radio receiver, utilizes double-differenced carrier phase measurements. The obstacle that the Counselman system must overcome for precise position, however, is the carrier cycle ambiguity.